No Dial Tone; Defective Mf Dial - Samsung SCX-4720F Service Manual

Troubleshooting
7.4 Fax & Phone Problems

7.4.1 No Dial Tone

• Description There is no dial tone when the On-Hook dial button is pressed.
Check and Cause
1. Check that the telephone line cord supplied with
the set is connected to TEL LINE correctly.
2. Listen for a CLICK sound when the OHD key is
pressed.
3. Check the connection of the HARNESS between
the LIU and the Main B'd.
4. Check that the SPEAKER is connected correctly.

7.4.2 Defective MF DIAL

• Description The MF DIAL is not functioning.
Check and Cause
1. Check that the telephone line cord supplied with
the set is connected to TEL LINE correctly.
2. Listen for a CLICK sound when the keKEY is
pressed.
3. Check the connection of the HARNESS between
the LIU and the Main B'd.
4. Check that the SPEAKER is connected correctly.
Service Manual
7-16
Solution
1. If the telephone cord is OK but there is no dial tone, try
plugging a normal telephone into the wall socket. I this
is OK then replace the LIU B'd.
2. If you cannot hear the OHD CLICK sound, the OPE
Ass'y may be defective. Replace the OPE Ass'y.
3. Check the Speaker connection and the harness
between the LIU and the Main PBA, replace as
necessary.
4. Use Tech mode / Modem Test to check that the
speaker and amplifier are working. Replace the Main B'd.
Solution
1. If the telephone cord is OK but there is no dial tone, try
plugging a normal telephone into the wall socket. I this
is OK then replace the LIU B'd.
2. If you cannot hear the OHD CLICK sound, the OPE
Ass'y may be defective. Replace the OPE Ass'y.
3. Check the Speaker connection and the harness
between the LIU and the Main PBA, replace as
necessary.
4. Use Tech mode / Modem Test to check that the
speaker and amplifier are working. Replace the LIU
and Main B'd in sequence
Notes: Product supports MF DIAL type only.
Samsung Electronics